My guess is the fact that existing jpeg images can be transcoded to jpeg-xl losslessly is the driving feature. This gives an easy migration path for existing si

My guess is the fact that existing jpeg images can be transcoded to jpeg-xl losslessly is the driving feature. This gives an easy migration path for existing sites that don't have high resolution masters that can be re-encoded into AV1 or webp. Also think of 20+ years of jpg digital camera photos that can now be transcoded to save space. For Apple that is also a huge win.